1. Field of the Invention
The present invention relates to a density calculating apparatus that calculates the print density of a color material when an image is printed in a printing system, a density calculating program storage medium, a density setting apparatus that sets the print density of a color material, and a density setting program storage medium.
2. Description of the Related Art
Conventionally, in a printing field, a print image has been formed by a series of processing where an image is edited by a personal computer and the like, a film original plate is made on the basis of the edited image, a plate is made on the basis of the film original plate, the plate is mounted on a printing machine and ink materials are applied thereto, and the applied ink materials are transferred onto a paper sheet. Further, in recent years, a CTP (Computer To Plate), which directly forms an image on a plate, is provided in a printing machine, and an automated digital printing machine, which can perform a plate making process and the like for acquiring a skilled technique, has been developed. Accordingly, the printing machine has been demanded as a printing machine for small quantity batch production that makes small quantity and various kinds of printed matters.
Meanwhile, a series of operations for performing printing on a paper sheet are massive operations of which a printing unit corresponds to several hundred copies, and large processing time or cost are required. Accordingly, before the actual printing operation, a proof image where a print image is reproduced is formed by a printer or the like more convenient than the printing machine, and the finishing of the print image is previously conformed by using the proof image. In addition, in the recent years, a proof image has been displayed on a calibrated monitor. Accordingly, it is possible to efficiently reduce the waste of a paper sheet, and to simply confirm an image of a print image in printing processes.
However, in the prior confirmation using the proof image, it is possible to confirm the design or the entire image of the print image. However, the color of the print image including the thickness of an ink material or the like or the finishing of the print image is confirmed by printing an image with the printing machine. In actual fact, the preferred thickness of an ink material varies depending on the print media, such as a newspaper, an advertising matter, a poster, and a magazine. Accordingly, when the print image is made, a user manually adjusts the print density of the ink of the printing machine until a desired color is obtained while the printing machine is driven and test printing is repeated. For this reason, there is a problem in that a large number of waste sheets are generated. Further, the number of waste sheets generated until the final print density of the ink is determined is substantially constant regardless of print copies. Accordingly, as the print copies are small, a ratio of the waste sheets is increased. Therefore, as for the digital printing machine for small quantity batch production, in order to reduce cost, it is important to shorten the time required until the print density of the ink is determined, and to suppress the generation of waste sheets.
In regard to this point, Japanese Patent Application Publication No. 2001-347645 discloses a technique where a forecast image where a print image is forecasted is formed on the basis of an opening degree value of an ink key that is used to adjust the print density of an ink material and a pixel value of image data, and a user manually adjusts the print density of an ink material while referring to the forecast image. Japanese Patent Application Publication No. 2004-106523 discloses a technique where a color coordinate value is acquired using an ICC profile on a halftone dot area ratio of a noticeable portion of a print image, the color coordinate value is set as a target density value, and the print density of an ink material is automatically adjusted so that a density value of a noticeable portion of a print image approaches the target density value. In the technique disclosed in Japanese Patent Application Publication No. 2001-347645, since the color of the print image can be broadly conformed before printing, it is possible to shorten the processing time required until the print density of the ink is determined. In the technique disclosed in Japanese Patent Application Publication No. 2004-106523, it is possible to easily adjust the print density of an ink material so that the color of a printed matter of the reference printing machine is reproduced by another printing machine.
However, in the technique disclosed in Japanese Patent Application Publication No. 2001-347645, in order to improve the forecast accuracy of a print image, the opening degree value of the ink key does need to minutely correspond to the pixel value of the image data, and the amount of data becomes huge. Further, it is possible to confirm the forecast image of the print image. However, an operation for finding out the print density of the ink required to correct the color of the forecast image into a desired color requires a skilled technique, and there is a problem in that it is difficult for an inexperienced user to adjust the print density of the ink.
Furthermore, in the technique disclosed in Japanese Patent Application Publication No. 2004-106523, until a target density value is achieved, the print density of the ink of the print image is finely adjusted while test printing is actually performed. Therefore, if an ink material of which the initial state is not optimally set, much time is required until the print density of the ink is stabilized. For this reason, there is a problem in that a large number of waste sheets are generated.